Due to the recent trend toward miniaturizing solid state imaging devices and improving the quality of pixels, several problems have been noted. For instance, sensitivity deteriorates because of a decrease in the photo-conversion area, and the smear characteristics degrade under the influence of oblique rays, since the space between adjacent photo-conversion parts has been reduced. Smear characteristic is a phenomenon that occurs when oblique rays from a photodiode generate free electrons at the bottom of a solid state imaging device and are captured by the solid state imaging device. In order to solve such problems, solid state imaging devices for general use are equipped with microlens layers on the photo-conversion part, or equipped with shading layers. The photo-conversion area should be decreased in order to improve the quality of miniaturizing CCD's pixels. Thus it may be necessary to miniaturize a photo-conversion body, which will shorten the focal length. As a result, a filter is required to be thinner so that it is easier to condense rays with a microlens. Furthermore, it is necessary to raise the photo-absorption rate of the shading layer in order to improve the smear characteristics, since the oblique rays influence on the smear characteristics.
As a method of manufacturing color filters, Japanese Laid Open Patent Application No. (Tokkai-Hei) 1-130102 discloses the use of m-nitrobenzenesulfonate and/or urea as dyeing assistant auxiliaries. A dyeing assistant auxiliary is used to promote dyeing.
However, the conventional method of manufacturing color solid state imaging devices causes problems such as surface roughness, which occurs when the surface of a filter becomes slightly rough or uneven. Desirable spectral characteristics cannot be easily obtained due to surface roughness.